Comparison of the pathogenicity of a Taiwan lineage 1 NADC30/34-like recombinant and a lineage 3 Betaarterivirus suid 2 in pigs

Porcine reproductive and respiratory syndrome virus 2 (PRRSV-2; Betaarterivirus suid 2 ) causes porcine reproductive and respiratory syndrome, leading to severe economic losses in the global swine industry. Lineage 1 (L1) PRRSV-2 has emerged and become increasingly prevalent in North America and Asia. This study compared the pathogenic characteristics of a Taiwan NADC30/34-like L1 recombinant and a lineage 3 (L3) PRRSV-2 strain and evaluated their suitability for establishing an experimental infection model in growing pigs. Ten-week-old pigs were inoculated with either the NADC30/34-like L1 NPUST-107-844/2018 strain or the L3 SW2018001-YL strain via concurrent intranasal and intramuscular routes. Pigs inoculated with the L1 strain exhibited higher body temperatures and a greater frequency of fever during the early post-inoculation period than those inoculated with the L3 strain. However, no significant differences were observed between the groups in peak viremia, lung pathological scores, or plasma cytokine concentrations. These results indicate that the Taiwan L1 strain induced a more pronounced early febrile response but produced virological, pulmonary pathological, and systemic cytokine responses comparable to those induced by the Taiwan L3 strain. Collectively, these findings highlight the pathogenic diversity of circulating PRRSV-2 strains in Taiwan and for future experimental studies, including investigations of disease pathogenesis, therapeutic interventions, and vaccine development.